Servo Drive


A servo drive is the device responsible for the continuous adjustment of deviations from the desired behavior as it is used in monitoring of the signal generated by the servo mechanism as feedback. It is an electronic amplifier but of a specialized kind which is used to power the electronic servo mechanisms.

The input of a servo drive is a command signal that is generated by the control system. The signal is then amplified. Then the motor receives the transmitted electric current which produces motion. This motion is directly proportional to the strength of the generated command signal. Usually it so is the case that the command signal is a direct representation of the desired velocity. But at times it can also be a representation of the preferred torque or position. The servo motor has a sensor attached to it and the function of the sensor is to give feedback to the servo drive about the current status of the motor. The drive then makes a comparison between the desired and the current motor status. And if there is any deviation of the current/actual status from the desired status, the drive regulates the voltage frequency or pulse width accordingly. When an appropriately programmed control system is used, the deviation of the actual rotational velocity of the motor is very small from that of the velocity signal that is sent by the control system to the servo drive. Numerous factors are altered and modified so that the desired performance is made a reality. The factors include stiffness, damping and feedback gain. Stiff is also referred to as proportional gain while damping can be referred to as derivative gain. The procedure in which these factors are adjusted accordingly, is known as “performance tuning”.

Nowadays, there are drives that are compatible with and extensive range of motors. However, there are still some servo motors that require drives with specific characteristics to function.

There are various industrial applications of servo systems including CNC machining, automation of factories and robotics. The feature of feedback from the motor is the biggest benefit of these systems over the conventional AC/DC motors. The feedback system makes it possible to detect undesired motion and to assure the precision of the signaled motion. Servo systems also have improved life cycles as compared to the conventional motors. They can also behave as brakes as they are able to shut off electricity from the motor.